JOURNAL OF THE JAPAN WELDING SOCIETY
Online ISSN : 1883-7204
Print ISSN : 0021-4787
ISSN-L : 0021-4787
Volume 50 , Issue 1
Showing 1-18 articles out of 18 articles from the selected issue
  • Mutsuo Nakanishi
    1981 Volume 50 Issue 1 Pages 5-11
    Published: January 05, 1981
    Released: August 05, 2011
    JOURNALS FREE ACCESS
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  • Makoto Sato, Kazunari Yamato
    1981 Volume 50 Issue 1 Pages 11-19
    Published: January 05, 1981
    Released: August 05, 2011
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  • Yoneo Kikuta, Takao Araki
    1981 Volume 50 Issue 1 Pages 19-28
    Published: January 05, 1981
    Released: August 05, 2011
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  • Junichiro Tsuboi, Yukio Hirai
    1981 Volume 50 Issue 1 Pages 28-37
    Published: January 05, 1981
    Released: August 05, 2011
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  • Yukio Hirai
    1981 Volume 50 Issue 1 Pages 37-46
    Published: January 05, 1981
    Released: August 05, 2011
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  • Kunihiko Satoh, Masao Toyoda, Fumiyoshi Minami, Toshiaki Fujimori, Ter ...
    1981 Volume 50 Issue 1 Pages 47-52
    Published: January 05, 1981
    Released: August 05, 2011
    JOURNALS FREE ACCESS
    NDT, in general, is performed for quality assuarance of welds. The reliability of welds, however, is affected by the defect detectability of NDT or the other inspection factors. In the present paper, an analysis method for getting the reliability of inspected welds is declared, and the controlling factors of the reliability of welds are discussed.
    The reliability of welds is decided by correlation of the defect detectability of NDT and critical defect level for repair. According to the defect detectability of NDT, therefore, critical defect level for repair Acr should be set smaller than critical allowable defect size acr.
    Deteriorating the defect detectability of NDT, the reliability of welds deteriorates. And the degree of deterioration of reliability depends on the sensitivity factor a0 and on the accuracy factor σA, but if a0 or σA is much smaller than acr improvement of NDT detectability does not always increase the reliability of welds. It is necessary to select the inspection procedure according to acr for QA of welds.
    In sampling inspection, the reliability of welds R is decided definitely according to average sampling ratio ps, and R-ps is in linear relationship. If the highly defective joints exist, the reliability of welds increases by performing sampling inspection with emphasis on those joints.
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  • Yoshihiko Mukai, Masato Murata
    1981 Volume 50 Issue 1 Pages 53-60
    Published: January 05, 1981
    Released: August 05, 2011
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    Stress corrosion cracking (SCC) tests were conducted in 42% MgCl2 aq. solution (143°C) on Type 304 stainless steel weld metals which exhibited δ+γ- duplex phase structure. Content of S ferrite was varied by heat treatment. Results are as follows:
    The SCC propagation rate in duplex weld metals is found to be delayed by δ ferrite contained. Generally, this phenomenon is called "keying action". And it was found that "keying action" acted more severely when δ ferrite distributed as network like in weld metal. In this study, to clarify the mechanism of "keying action", electro-chemical measurements were performed by potentiostatic method.
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  • Kotoji Ando, Yuji Yasuda, Nobukazu Ogura
    1981 Volume 50 Issue 1 Pages 61-64
    Published: January 05, 1981
    Released: August 05, 2011
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    The susceptibility of weldments to hot straining embrittlement has been examined in detail. Three points bend specimens were extracted from the welded joints of HT 80 and SM 50 steels. Then sharp notch was accurately machined on fine grained HAZ, coarse grained HAZ, weld metal and base metal in each other. After machining the notch, one groupe of specimens was hended at 250°C to receive the saturated hot straining embrittlement, and then they were-tested at temperature of interesting by measuring critical crack opening displacement to fracture. For the case of the weldments of HT 80, hot strained coarse grained HAZ showed the highest transition temperature in the weldments (fine grained HAZ, coarse grained HAZ, weld metal, base metal). For the cae of the weldments of SM 50, weld metal and coarse grained HAZ showed nearly same degree of hot straining embrittlement and these regions showed higher transition temperature than base metal and fine grained HAZ, when they received saturated damage.
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  • Junichi Kinugawa, Sadao Fukushima, Takeshi Fukushima
    1981 Volume 50 Issue 1 Pages 65-70
    Published: January 05, 1981
    Released: August 05, 2011
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    Transformation behavior of coarse-grained regions during underwater wet welding and some resulting characteristics were investigated by comparing with those of welding in air.
    JIS-SM type steels between SM41A and SM58Q were used as the base metal.
    The results are summarized as follows:
    1) Starting temperature of ferritic transformation during cooling of underwater wet welding is lower by about 20-25°C over the range of Ceq (JIS G 3106) from 0.33 to 0.41% and slightly lower for the Ceq of 0.44% than that during cooling of welding in air.
    On the contrary, Ms is higher within the limit of some 30°C for the Ceq of 0.33%. The difference is gradually reduced as Ceq becomes still higher and hardly found for the Ceq of 0.44%.
    2) For the amount of martensite between 50% and 10%, cooling time from 800 to 500°C during underwater wet welding is longer within the limit of nearly 90% than that during welding in air.
    3) In case that the "coarse-grained regions near the center of bond" of an underwater wet weld and a weld in air contain the same amount of martensite, the "coarse-grained regions near the toe" of both the welds also contain almost the same amount of martensite.
    4) In case that the coarse-grained regions of an underwater wet weld and a weld in air contain the same amount of martensite, no significant difference is found in their hardness.
    5) In the same case as above, no significant difference is found in their elongation at crack initiation, too.
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  • Kunihiko Satoh, Masao Toyoda, Shuhei Okamoto
    1981 Volume 50 Issue 1 Pages 71-77
    Published: January 05, 1981
    Released: August 05, 2011
    JOURNALS FREE ACCESS
    The study has been made on fractur behavior of welded joints with defects in steel framed structure, especially, of column-beam welded connection. The connection is required sufficient load capacity and/or ductility to resist against large earthquakes. Therefore, in steel framed structure, general yielding fracture behavior of welded joints should be investigated.
    In this report, static tensile tests and elastic-plastic 2 dimensional F.E.M. analyses of welded joint with notches were carried out, considering 3 fracture controlling factors (notch toughness, notch length and reinforcement).
    In the fracture testing of these connections, fracture mode is divided into two types; that is, one is ductile fracture and the other is general yielding brittle fracture. In steel framed building, the fracture mode depends on notch toughness rather than notch sizes. Therefore it is much important to control notch toughness.
    Reinforcement increases fracture load, but it does not increase ductility.
    At general yielding stage of welded joint with notches, COD at notch tip is nearly proportional to overall strain ε∞ in sufficient large gage length. For column-beam welded connection made by C-Mn steel, non-dimensional COD δ'-εy relation is given by the following equation.
    δ'=δ/2πεya=0.6(ε, εy)
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  • Atsushi Hasui, Takashi Matsui
    1981 Volume 50 Issue 1 Pages 77-83
    Published: January 05, 1981
    Released: August 05, 2011
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    This report deals with the effect of faying face condition on welding phenomena and mechanical properties of the welded joint in friction welding. The experiments were carried out by a continuous drive type friction welding machine. The base material used was 0.25% carbon steel.
    Conditions of faying face are labelled as,
    A: Clean face degreased with benzine.
    B: Greased face.
    C: Face covered with oxide film, which is made by keeping the specimen at 370°C for 1 hour.
    D: Face with a drilled hole of 1 mm in diameter and 3 mm in depth.
    Main results are as follows,
    (1) The joints made under conditions A, B, C and D break at base metal in both tensile and fatigue tests, and have sufficient ductility in bending test.
    (2) In case of condition B, grease on the faying faces is extruded from weld interface within 0.5s after base metals contact.
    (3) The existence of oxide film, having about 0.1 μm in thickness, on faying face does not affect welding phenomena and weldability. However, when the oxide film becomes thicker, it decreases coefficient of friction and forbids the rise of initial torque. In this case the oxide film causes delay in starting burn off, and the delay time is proportional to the square of thickness of oxide film.
    (4) In case of condition D, the dark layer is observed at weld interface and is vicinity, i.e., track of air from drilled hole. It is considered that the layer is shaded by the finely distributed oxide particles.
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  • Hiroshi Ikawa, Hiroaki Oshige, Hirohiko Date
    1981 Volume 50 Issue 1 Pages 83-87
    Published: January 05, 1981
    Released: August 05, 2011
    JOURNALS FREE ACCESS
    In the previous papers, it was made clear that the width of recrystallized soft zone in HAZ of cold rolled material could be calculated by combining the recrystallization equation with the heat conduction equation in welding.
    On the other hand, the method to estimate the strength of welded joint including soft layer has been proposed.
    Therefore, in this paper, a method to escimate the strength of welded joint of cold rolled material was proposed by combining the two methods mentioned above.
    Then, the validity of this method was confirmed on electron beam welded joints of cold rolled com-mercial-purity aluminum. That is, strength of joints with and without filler metal coincided fairly well with the estimated values.
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  • Shigetsugu Asakura, Masayasu Nihei
    1981 Volume 50 Issue 1 Pages 87-93
    Published: January 05, 1981
    Released: August 05, 2011
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    Weldability as related to the heat-affected onzes of the steels, Ni-Cr(SNC22) and Si-Mn(SM50B) were investigated by making the SH-CCT diagram, V-charpy impact and micro-tensile test of synthetic HAZ specimens and the slit type cracking test. The results of these test are summalized as follows.
    (1) The impact value of synthetic heat-affected zone changes according to a cooling time. Regions of cooling time (800-500°C) to obtain the highest impact value are less than l5sec for steel SNC22 and 11-21 sec. for steel SM50B.
    (2) The impact value of synthetic HAZ after postheating (600°C, 2hrs) is remarkably improved when the cooling time of the thermal cycle is less than 10sec (100% martensite) for SNC22 and more than 21sec (bainite+Ferrite) for SM50B.
    (3) In multi-pass weld joint test, the effect of cooling time (800-500°C) after welding on the impact value of the HAZ agrees well with the tendency in the result of the thermal cycle test.
    (4) In the slit type cracking test, when the amount of the bainite structure of the HAZ is approximately more than 45% for SNC22 and more than 65% for SM50B, the HAZ cracking can be prevented even if wet covered electrode (12ccH2/100 g) is used.
    (5) When the slit type cracking test specimens were welded by the TIC welding process, the HAZ crack-ing cannot be recognized even under no preheating conditions for each kinds of the test steels.
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  • [in Japanese]
    1981 Volume 50 Issue 1 Pages 96-100
    Published: January 05, 1981
    Released: August 05, 2011
    JOURNALS FREE ACCESS
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  • [in Japanese]
    1981 Volume 50 Issue 1 Pages 101-106
    Published: January 05, 1981
    Released: August 05, 2011
    JOURNALS FREE ACCESS
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  • [in Japanese]
    1981 Volume 50 Issue 1 Pages 107-113
    Published: January 05, 1981
    Released: August 05, 2011
    JOURNALS FREE ACCESS
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  • [in Japanese], [in Japanese]
    1981 Volume 50 Issue 1 Pages 114-119
    Published: January 05, 1981
    Released: August 05, 2011
    JOURNALS FREE ACCESS
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  • [in Japanese]
    1981 Volume 50 Issue 1 Pages 120-125
    Published: January 05, 1981
    Released: August 05, 2011
    JOURNALS FREE ACCESS
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